Air dryer purge valve corrosionPhoto courtesy of Bendix
Inspections should also include an eye for cracking or breakage of plastic air-line tubing that connects the dryer to the truck’s air system. Push-to-connect air fittings can also be affected by chemicals and temperature cycling.
In the cab and on the road
Behind the wheel, there are other indicators of winter damage to an air brake system.
“Just because you don’t immediately see or hear any leaks doesn’t mean they’re not present,” Nagel said. “If you notice that it’s taking significantly longer to charge the tanks – say, three or four minutes compared to one or two – then that’s a sign that your air brake system is losing air. The same thing applies if you notice the system charging more often. And an increase in charging cycles also means more air going through the dryer, which affects the life of the dryer cartridge.”
Additionally, if the air dryer cartridge wasn’t replaced in the fall, he added, then spring is a good time to switch it out.
Drivers might also notice a general “stickiness” in the feel of the brakes, as if they’re responding more slowly to the push of the brake pedal. This can also indicate valve seals in the system that have had their lubricant degraded through corrosion, or possibly by the use of de-icing solutions if the air system froze during the winter.
“That’s why we never recommend adding anything to the air system – although we recognize that some situations may call for the drastic measure of using a brake anti-freeze compound,” Nagel said. “If you’ve had to do this, then spring is a great time to check for leaks around brake valves where O-rings might have been exposed to these chemicals or replace valves that may be sticking internally due to loss of lubrication. Some fleets even routinely just change out air valves as part of post-winter preventive maintenance.”
It’s all connected
Higher-level air-connected technologies like antilock braking systems (ABS) can also suffer from difficult winter conditions.
“Wire harnesses get chipped by gravel or experience corrosion, and once the wires get wet, they can short out,” Nagel said. “Any wiring on the chassis is at risk, and our technical support team says post-winter electrical shorts and the resulting air brake valve malfunctions are the number one source of calls to Bendix this time of year.”
As more trucking systems depend on a reliable supply of compressed air – including Automated Manual Transmissions (AMTs), emissions controls, and full stability – proper maintenance of the air system is key to keeping vehicles on the road and in good operating condition. This spring, spending some extra time addressing the ravages of winter can help enhance fleet safety and ease the road ahead for the men and women at the wheel.
Information from the Bendix Tech Tips series can be found in the Bendix multimedia center at knowledge-dock.com. Further instructional videos and interactive training on wheel-end technologies are available at the Bendix YouTube channel.